1. Field of the Invention
The present invention pertains to a paper supply apparatus (paper feed cassette) capable of being used in a copier, printer, or other such image forming apparatus, and more specifically pertains to a paper supply apparatus capable of being used in a front-loading-type image forming apparatus in which placement of paper therein is accomplished as a result of operations carried out at the near side of the apparatus.
1. Description of the Related Art
A front-loading-type image forming apparatus might be such that an original stage, scanning unit, image forming unit, and discharge tray are arranged at the upper part of what is, for example, a vertically oriented apparatus main body; and such that a paper feed unit is arranged at the lower part thereof. The paper feed unit might be equipped with a cassette compartment, the paper supply apparatus (paper feed cassette) being loaded into the cassette compartment upon being pushed from the near side of the apparatus main body toward the far side thereof. Furthermore, during filling of the paper feed cassette, placement of paper therein might be accomplished by means of a sequence in which the paper feed cassette is pulled out to the near side of the apparatus, paper is placed within the paper feed cassette, and the paper feed cassette is thereafter again pushed thereinto.
As shown in FIG. 17, as an example of a paper supply apparatus capable of being used in such a front-loading-type image forming apparatus, there is paper feed cassette 401 which is provided with a positioning mechanism made up of two paper guides 431, 432 having rack gears 433, 434; paper-separating tabs 435, 436; pinion gear 404 meshing with respective paper guide rack gears 433, 434; paper trail edge plate 406; and so forth (see, e.g., Japanese Patent Application Publication Kokai No. H10-129856 (1998)).
At paper feed cassette 401 shown in FIG. 17, the paper feed direction is perpendicular to the direction in which the cassette is inserted into the image forming apparatus (loading direction). Furthermore, in order to facilitate filling of paper feed cassette 401 with paper, paper guides 431, 432—respectively located at the far and near sides thereof—are arranged so as to permit sliding motion in the loading direction. These two paper guides 431, 432 are such that respective rack gears 433, 434 mesh, as has been said, with a single pinion gear 404, movement of one of the paper guides (e.g., near-side paper guide 431) causing the other paper guide (far-side paper guide 432) to move in linked fashion therewith. Moreover, as shown in FIG. 18, paper feed cassette 401 is provided with rotating plate 407 for lifting upward the paper which has been placed within paper feed cassette main body 402.
However, with a conventional paper feed cassette such as that capable of being used in a front-loading-type image forming apparatus, because during placement of paper therein a user might position a stack of paper by causing same to strike and abut the far-side paper guide, thereafter lowering the near side of the paper into the cassette, a large impact might be exerted on the far-side paper guide. Furthermore, after the paper has been placed within the paper feed cassette, when the paper feed cassette is pushed into the image forming apparatus, an impact occurring at the conclusion of insertion of the cassette, i.e., an impact arising due to the weight of the paper, might again be exerted on the far-side paper guide. Because impact exerted on the far-side paper guide in such fashion during placement of paper within the paper feed cassette and/or insertion of the paper feed cassette into the image forming apparatus can cause mechanical play to arise in the far-side paper guide, affecting positioning of the paper guide, this may produce variation in location(s) at which paper is constrained by guide(s) and/or failure of paper to be held by paper-separating tab(s).
The present invention was conceived in order to eliminate such problems, and provides a paper supply apparatus permitting elimination of paper transport problems and capable of preventing de-positioning of paper guide(s) and/or the like that might otherwise occur during filling of paper feed cassette(s) in the context of front-loading-type image processing apparatus(es).